1. Field of the Invention
The present invention relates to a navigation apparatus and position detection method, and is preferably applied to a navigation apparatus mounted on a vehicle, for example.
2. Description of Related Art
Generally, a navigation apparatus receives from positioning means (such as a Global Positioning System (GPS) satellite) the positioning information (i.e., the GPS signals) to calculate the current position of a vehicle and then displays it on a screen. However, as disclosed in Patent Document 1 (see Jpn. Pat. Laid-open Publication No. 2004-138553), when unable to receive the GPS signals due to the vehicle running inside a tunnel or the like, the navigation apparatus calculates the vehicle's acceleration in the direction of the vehicle's motion based on data detected by an acceleration sensor and then estimates the vehicle's speed. The navigation apparatus subsequently estimates, based on the estimated speed, the current position of the vehicle, which is then displayed on a screen.